In the summer, incorrectly detached attics can cause high energy bills and premature aging of roof material. In winter, this can lead to accumulation of moisture in the attic and lead to mold and even problems with mold. If you ask ten different roofing systems contractors for roof ventilation, you will most likely get ten different answers. And, most likely, none of these contractors can tell you which ventilation workshops they attended. Their opinions are formed freely around rumors.
Some common ventilation myths that misinform contractors are to blame for the spread:
- You can add a vent to an existing ventilation system. No.
Mixing different types of air vents can result in undetectable patterns that interrupt the free flow of air. Different types of valves can actually cancel each other. Existing turbines or low profile vents should be closed if the ridge fan is installed.
-Installation of low-profile ventilation holes on both sides of the roof peak doubles the exhaust. No.
If you place the ventilation holes across the ridge from each other, one side will act as a reception for the other and in fact push the warm air on them to the attic floor (ceiling for residential premises).
- Power ventilation grilles - the best thing. No.
Power vents heat up with a thermostat and, as a rule, do not work to move air during the coldest months of winter, which allows moisture to accumulate. Thermostats in the ventilation ducts are very temperamental and usually break during the first two years. They need an electrician to install, and they run away from your electricity, which makes them attractive. On the other hand, solar fans are excellent products today, and they do not have any of the negative impacts of traditional power vents when properly installed.
- More ventilation is better. Not necessary.
Too large attic ventilation can suck conditioned air from the living room and become counterproductive. The ratio adopted by UBC, FHA and SBCCI (major construction agencies) is 1/300, however 1/150 is recommended for warmer summer climates. That is, one square foot of ventilation for every 150 square feet of attic space. Then this number is divided even between the entrance and the exhaust. According to this formula, a 2500 square foot loft needs 13 square feet of ventilation (2000/150). This number should be divided into two, 6.5 square feet for taking and 6.5 for exhaust. For reference, one wind turbine or four feet of the ridge air inlet is one square foot of exhaust. Two vents for soffits cost one square foot. For a 2,000 square foot loft, you'll need thirteen spotlight vents and a 26 foot ridge vent or 7 turbines.
The most important thing to remember is that without an air intake, the ventilation grilles are useless. If you do not have soffit ventilation, call a reliable local contractor to evaluate. If you have holes for soffits, make sure they are free of dirt and insulation. If you have special circumstances, such as cathedral ceilings or eaves, you should ask a qualified roofing contractor for a more creative solution. You can also ask more specific questions about ventilation in the homeowner's forum at http://www.hailandwind.com/
